Surface passivation of high‐efficiency silicon solar cells by atomic‐layer‐deposited Al2O3

Abstract Atomic‐layer‐deposited aluminium oxide (Al 2 O 3 ) is applied as rear‐surface‐passivating dielectric layer to passivated emitter and rear cell (PERC)‐type crystalline silicon (c‐Si) solar cells. The excellent passivation of low‐resistivity p ‐type silicon by the negative‐charge‐dielectric Al 2 O 3 is confirmed on the device level by an independently confirmed energy conversion efficiency of 20·6%. The best results are obtained for a stack consisting of a 30 nm Al 2 O 3 film covered by a 200 nm plasma‐enhanced‐chemical‐vapour‐deposited silicon oxide (SiO x ) layer, resulting in a rear surface recombination velocity (SRV) of 70 cm/s. Comparable results are obtained for a 130 nm single‐layer of Al 2 O 3 , resulting in a rear SRV of 90 cm/s. Copyright © 2008 John Wiley & Sons, Ltd.